I ENDURO STAINLESS ALLOYS ENDURO S— Chromium 13%, carbon under .12%. Suit- able for applications where moderate corrosion resistance combined with high strength and toughness are required. Oxidation resistance to 1500° F. ENDURO FC— Similar to "S" but with free machining qualities added. ENDURO AA— Chromium 17%, carbon under .10%. For applications where corrosion resistance is more important than high strength or toughness. Good bending and form- ing qualities. Oxidation resistance to 1600° F. ENDURO KA2— Chromium 18%, nickel 8%, carbon under .16%. Excellent general corrosion resistance to atmos- •here, salt air, food and dairy products, nitric acid, etc. High ductility and best drawing qualities. Oxidation resis- tance to 1600° F. ENDURO KA2S— Similar i KA2," but with carbon under .07%. For applications requiring high physical properties above 1000° F. and for welded fabrication where subsequent heat treatment is not possible. ENDURO KA2B— Similar to "KA2/' but with added sili- con. Oxidation resistance to 1700° F. ENDURO KA2Mo— Similar to "KA2" but with 3% mo- lybdenum added. ENDURO HC— Ch mum 28%, carbon under .20%. De- igi 1 for oxidation ance to 2100° F., where great •ngth and toughness are not required. High resistance to sulphur and sulphur ga^es, hot or cold. I NDURO HCN— Chromium 23%, nickel 12%, carbon i !er .20%. Oxidation resistance to 2100° F., \ h physical ] gher than "KA2S." ENDURO KNC-3— Chromium 25%, nickel 217c, carbon under .25%. For applications requiring highest strength and nidation resistance at highest temperatures. NDURO KA2. KA2S KA2B, KA2Mo, HCX and KNC-3 are produced undtr Krup] a patents. . • » M s OST present or prospective users of stainless alloys have at some time been conscious of a lack of accurate basi< information which would permit them to select intelligently and to fabricate successfully the par- ticular type of stainless best suited to a »i\en re- quirement. Obviously, no single type can meet all conditions of corrosion and temperature. A series of booklets has therefore been prepared to supply thi e\;iet information on the Enduro Stainless Irons. Stainless Iron generally is an allo\ of iron and chromium, or of iron, chromium and nickel, with ver\ low carbon content. The stainless properties of the alloy are due to the ability of chromium to form with iron a solid solution which is resistant to the various corrosi\e media. It is essential that sufficient chromium be present in solid solution t<. ensure stainless properties. The chromium con- Th e RO STAI LESS ALLOYS tents of Enduro Stainless Irons have been adjusted accordingly , Stainless irons as a class do n<>l respond to hard- ening 1»\ heal treatment. Neither do the} require special heal lieatment other than thai received al the mill to develop stainless properties. Stainless irons a- a class lend themselves to deep drawing and other forming operations. There is a distinction between stainless iron and stainless steel, though the latter term is popularly if erroneously used lo desj^nale all stainless alloys StrietU speaking stainless steel is an alloj of iron, chromium and carbon. The amounl of carbon i Mich that the material harden* upon quenching. This branch of the stainless family is suitable for cutlery and applications where high physical prop- erties, hardness and wear resistance are required, but does not lend itself to deep drawing or forming. Not only does stainless steel require very careful Selection of Type and Finish — Enduro polishing, but it must also be carefully heat treated before polishing to develop its corrosion-resisting properties. Types of Enduro Stainless — To meet the de- mands of industry for corrosion- resisting alloys suitable for a wide variety of specific purposes, the Enduro Stainless Irons have been developed in a number of types. In this development all factor- ail ting corrosion resistance have been considered nd their relative importance established. The esult is a series of alloys possessing maximum corrosion resistance and physical properties, con- sistent with ease of workability, for each field of ipplication. ll is noteworthy that this has been accomplished without undul) increasing the cosl of I he alloys. Stainless Irons are furnished in several different finishes. The finish of the stock used will depend on the amount of forming necessary. Jt is inadvis- able to use polished sheets for extra deep drawing operations where score marks from dies are likeh to occur in forming or where it is necessary l<. re- anneal to make a second drawing operation. An unpolished, fully annealed and pickled sheet designated as our number one (1) finish should be used. Polished finish should he used onl\ where stock will be employed without further working or where the degree of working is small. Corrosion Resistance Much harm has been done by exaggerated claims of corrosion resistance. Metals and alloys are resistant to corrosion in dilT erent degree, none being entirely proof against all corrosive agent-. Each melal or allo\ is limited as to the field in which ii is serviceably resistant; hence while it may possess excellent resistance in its field, it by no means follows that it will be equally resistant to all attacking media under all conditions. To simplify this problem we group the application of l he Enduro Stainless Irons under three headings: 1 . Atmospheric Corrosion — understood t«» mean exposure to weather conditions. 2. Wet Corrosion — understood to mean partial or total immersion in corrosive liquids. :5 . Dr\ Corrosion — understood to mean seal- ing at elevated temperatures. Atmospheric Corrosion — In this field the Enduro Stainless Irons are excelled by no other stainless alloys. The higher the allo\ content of each Enduro type, the more resistant I he alloy is to corrosion by weather exposure. In addition to this result from higher content of alloys, the form- ing and deep drawing qualities also are favorabh influenced, particularly b> the addition of nickel. Ml types of Enduro Stainless Irons produced b\ Republic Steel Corporation are suitable for general resistance to atmospheric corrosion. Wet Corrosion — Enduro Stainless Irons are resistant to nitric acid and similar oxidizing agents. to sulphur and sulphur compounds and to the more common organic acids occurring in the household. They are not resistant to hydrochloric or sulphuric acids except under special conditions. The rate at which corrosion (solution of the allo> in the corrosive liquid) takes place depends upon a number of factors, among which are the con- centration of the other elements in the solution and the character of the solvent; the temperature; the ^late of the solution, whether agitated or at rest; the amount of dissolved oxygen or other oxidizing agents present; the presence of impurities in the solution which might act as inhibitors, or them- selves attack; electrolytic action because of contact with other metals, etc. Since these and other factors affect the rate at which corrosion takes place, it is questionable whether laboratory tests on the stainless irons are of great practical value except insofar as the> in- dicate whether attack does or does not take place and if it does, whether rapidly or slowly. Tests on samples of Knduro Stainless Irons under actual conditions are much preferable to calculations of probable corrosion rate based on laboratory data. The Republic Steel Corporation has a large amount of corrosion data obtained from bests in pun solutions and also from actual application of Ih various alloys under service conditions. If the pro- spective user of Enduro Stainless will submit the application to our metallurgical department a recommendation will be made. Dry Corrosion — Enduro Stainless Irons are resistant to scaling at elevated temperatures. Each type is best suited for certain conditions and tem- peratures. All Enduro Stainless [rons are resistant to sulphur gases up to 1000°F. In dealing with the application of Knduro Stainless Irons to high temperature service it is important to differentiate between intermittent and contin- uous service. This is necessary because >me of the stainless alloys have a tendency to cast ofF their protective scale when alternately healed and cooled. due to difference in the coefficient of expansion between the scale and the metal itself. There ha> been established a maximum temperature foi these service conditions which is given for each t \ pe of nduro. Physical Properties at High Temperatures \ selecting a material for the design of equipment which is to be used under high temperature conditions, where high stresses ma\ he encountered, as in oil refiners operations, the following qualifications are neces- ar\ : (;«) The metal must have tin* requisite strength at the sprrilh'd lemperal ure. (\>) l\ must not oxidize under ihe action of tin- Name or hot gases. (c) 1 1 iim-i noi heroine brittle while in service. (d) It must n isl Lhe corrosive action of the materials with v\ hich it is in conl u I -urh us liquids, pases, etc Enduro on th« Chryvl«r Tc I ' I e 1 1 * t r e r \i I m- i a r i I \ d « MM! | r li 'lli| || K*s Ih.l L| .1 illy * il h the rati tt w hi* h in plied. But when the test is made at high temperatures the rate of pulling of the tensile lest piece has a marked effect on the ultimate tensile strength obtained. The more slowly t lie test piece is pulled, the lower is the strength shown by it- It is thus apparent that the tensile strengths of metals at high temperatures as ordinarily determined by short-lime tests cannot be used tor design purposes. It is equally evident that the effect of stress on the metal held ai a high temperature for a long time must he known before it is possible intelligently to design equipment to be used under- such conditions. I f the strength of a meial at a given high temper- ature is determined onl> b> ordinary tensile tests. piece of equipment subjected to that temperature lor i longer time, under pressure, using a safe liber Lress as determined l>> ihe short-time tests, will pr< -i\el\ stretch, or "creep." This will con- tinue until a point is reached where the metal thickness becomes so greath reduced thai the pressure can no longer be withstood, and the ap- paratus will fail. li is well to note thai this reduction in the thickness of the metal ma> also be hastened b> the effects of rrosion n of oxidation, or a combination of both In order to design apparal us or equipment suitable for service at various H«-\ aicd temperatures, when stn i - will be high, il is necessary to determine the • reep strength* 1 of the metal. The "creep strength" i a given temperature ma) therefore be defined as ih« tress .ii which the metal will elongate r, during 1 00, 00 n or lu.noo I - ad that temperature The n ep strength* 4 of ea<-h Knduro type, mpared to plain carbon steel in given in com pai m undei i h i ype. In applying this data i problems of practical design Jes should be | <| correspond ii to the highest temperatures an- i ieipated i i fai o»r of -;dei \ iDtrodu< ed to prevent d- 4 1 s being em ceded, should the temperature l< ri I all \ be in <! i A Few of the Polishing Machines in Republic's Finishing Division Preparation of Surface Polishing HE preparation of the surface to be exposed to corrosive attack is of the utmost importance. When the highest degree of corrosion resistance is desired, the scale resulting from hot working must be removed and the surface ground and polished. To secure the permanent, beautiful, silver-white lustre characteristic of Enduro Stainless Irons, which permits them io replace such materials as nickel plate, chromium plate, nickel silver, tinned copper, and the copper nickel alloys, it is necessary that certain precautions be observed. Polishing and buffing equipment which has been used for polishing other metals should have all such metal particles carefully removed before use in polishing Enduro. Careful selection of polishing grits and buffing compounds is necessary to insure their freedom from iron, as otherwise such iron ma> be worked into or remain on the surface of the polished article and will under corrosive conditions give the erroneous impression thai the stainless alloy i^ rusting. V factor of equal importance is that all surface imperfections must be removed to secure maximum corrosion resistance. In polishing flat surfaces it is necessary to begin operations with coarser grits than when polishing formed articles. The rule should be to use the finest abrasive possible and m yel remove all of the surface imperfections, the that coarse grit marks are verv than (hat of polishing, 7200 to 12000 lineal feet per reason being difficult to remove. A polishing speed of from 5000 to 7000 lineal feet per minute is productive of very good results. The first few polishing operations may be done dr> . but the final operation should be done on greased wheels. Care must be exercised not to burn the work, the lower coefficient of thermal conductivity making this danger greater than when polishing copper, brass or steel. The bulling of Enduro Stainless Irons must be done with iron-free bufling compound. This precludes the use of ordinary jeweler's rouge. Green chrome oxide is a suitable material where a mirror finish is not necessary; however, when such a finish i- necessary special buffing ((impounds are required followed by the use of chromium oxide to bring out the color. The speed of bufling should be higher minute. As regards polishing, the character of the finish of the exposed surface is the most important factor in producing resistance to stain and tarnishing; hence, the more perfect the finish, the less the like- lihood that the metal will slain. When formed articles do not require maximum resistance to corrosion and are to be used in I lie "as drawn" or semi-polished condition, it is recom- mended that the article be given a passivation or cleansing treatment. When using stainless iron in the semi-polished con- dition there will usualW be some 4 discoloration of the exposed surface. This eventually develops into a permanent, tightly adherent surface coating which, if appearance is not a primary consideration? does not adversely affect the life of the metal. Passivation of Enduro Stainless Alloys Polished sheets as furnished for exposure to weather conditions are given a special surface treatment before shipment from Republic Steel Corporation, This treatment is known as a "Passivation Treat- ment and insures proper resistance to corrosion, staining, and discoloration. In installing such polished sheets on buildings the fabricator will often find it necessary to cut, machine, punch, shear, bend, or otherw ise work the metal with the result that the passivated condition is destroyed. In forming the sheet the forming tools It impossible to immerse pieces, all sheared edge drilled or punched holes, engraved or scratched surfaces should be swabbed or scrubbed with the above nitric acid solution. 3. Rinse in clear water to remove all traces of acid, and dry. usually are made of regular die steel. There is a possible abrading action between the stainless metal and the steel die which may leave a surface film of iron on the stainless surface after the forming opera- tion. This film should be removed by the passivating treatment as otherwise a form of rusting wi appear after the unit is placed in service. With certain forming operations it is possible to use paper or other lubricating compounds between the stainless metal and the steel die, which will prevent the abrading action. Cleaning of Polished Enduro— To keep polished Enduro surfaces clean, use soap and water, with a 4 'grease free" drying and polishing cloth. \\ here necessary to use a polish, Bon Ami is recom- mended. Do not use liquid metal cleaners, as they are liable to dull the lustre. Tile and brick cleaning compounds are likely l<» contain ingredients which may etch or discolor Enduro Stainless and il is therefore recommended that when Enduro is installed in conjunction with ■ (ile or brick it be wiped with a greasy cloth to protect the surface when the lile is cleaned. Use o f Contact with Other Metals — The polished Enduro Stainless sheet and trim on I be Where this is not possible it is recommended that outside of buildings may necessitate the use of after such operations the metal surface be repas- steel supports that are welded or otherwise attached to the stainless metal and then attached to the steel structure of the building. These points of contact of steel to stainless should be protected from cor- rosion as much as possible; a coating of paint is recommended. sivated in I lie following manner; 1. Wash thoroughly in kerosene to remove all traces of grease, drawing compounds, etc, and dry by rubbing with whiting. 2. Immerse in a 20% by volume solution of commercial nitric acid at a temperature of 130°F. for 20 to 30 minutes. This acid will not attack ihe metal nor destroy the surface finish. (Tanks for holding such acids should be lined with stain- less alloy.) The contact of Enduro Stainless with other metal should be avoided where electrolytic corrosion i- apt to occur (wet corrosion). Under all other condi- tions, it is satisfactory to have Enduro Stainless in contact with dissimilar metals. Applications Following are a few of the applications in which the various types of Knduro have met with conspicuous success. Enduro K A 2 Bottling machinery. Canning and preserving equipment. Cold storage plant apparatus. Cooking utensils. Dairy and milk handling machinery. Dyeing, bleaching and finishing machinery. Exterior building trim. Ham boilers. Household electrical appliances. Ice cream freezers and cabinets. Laundry machinery. Washing machines and parts. Meat slicing machine parts. Packing house equipment. Paper and pulp machinery. Electric refrigerator parts. Restaurant equipment. Salt dryer>. Soap making machinery. Soda fountains and counters Sterilizers. Street lamps. Sugar refinerj machinery. Enduro A A Abattoir equipment. Bakery equipment. Bottling machinery. Builders' hardware. ( andy making machinery. Canning or preserving equipment Chemical plant apparatus. ( looking utensils. ( iolf club heads. Ice making machinery. Nitric acid planl equipment. Nitrogen fixation apparatus Oil refinery equipment. Pyrometer protection tubes. Recuperators. Rubber plant machinery. Septic tanks. Scientific apparatus. Soot blowers. Tanks — all kinds. Varnish ket ties. Etc., etc. Enduro S Automobile parts such as pump shafts, etc Heater bars for paper mills. Gage and indicator parts. Locomotive safety valve seats. Mining i chiner^ and equipment. Hitle and revolver barrels. Pumps or pump parts. Railroad equipment . Steam turbine parts. Shafts for deep well pumps. Valve parts for high pressure steam, and oil refinery equipment. Parts requiring high phvsical proper! ies. f or Knduro is available in bars, castings, forcings, plates, sheets, strip, tubing, *ire and innumerable finished products through fabricators. REPUBLIC STEEL CORPORATION YOUNGSTOWN, OHIO Vdv. Printed in I . S. \. I [BLANK PAGE] CCA INTFRN ATIOMAI DISTRIBUTED BY FRETZ BRASS COPPER CO 523 ARCH STREET PHILADELPHIA .